Euthelepus aserrula, Hutchings, Pat, Nogueira, João Miguel Matos & Carrerette, Orlemir, 2015

Hutchings, Pat, Nogueira, João Miguel Matos & Carrerette, Orlemir, 2015, Telothelepodidae, Thelepodidae and Trichobranchidae (Annelida, Terebelliformia) from Lizard Island, Great Barrier Reef, Australia, Zootaxa 4019 (1), pp. 240-274 : 251-252

Euthelepus aserrula n. sp.

( Figs 6–7 )

Type material. Holotype: AM W.47509, Martin Reef, back reef, 14°45'22"S, 145°21'46"E, coarse coral rubble, 3– 15 m, 30 Aug 2010: incomplete specimen, with 30 segments, notopodia until segment 23 on left side of the body and 25 on right side; 9 mm long, 1.0 mm maximum width (segment 6).

Description. Holotype incomplete. Transverse prostomium attached to dorsal surface of upper lip; basal part with eyespots in two groups, one broad band of large, dark red, rounded eyespots at each lateral near anterior margin of basal part of prostomium, few eyespots continuing dorso-laterally and conspicuous mid-dorsal gap, and another group of minute light red spots forming continuing row across dorsum, at posterior margin of basal part of prostomium; distal part low, restricted to base of upper lip ( Fig. 6 A–B, D–I). Few buccal tentacles remaining, short and thick, stout, deeply grooved, reaching to about segments 6–7 ( Fig. 6 A–J). Peristomium forming lips and continuing dorsally; upper lip short, hood-like, slightly wider than long; lower lip short, just around mouth, partially hidden by ventral lobe of segment 1 ( Fig. 6 A–B, D–I). Segment 1 narrow, with ventral lobe marginal to mouth; short lateral lobes on segments 2–3; lobes triangular, about same size, those on segment 2 wider, ventrolateral, lobes on segment 3 placed laterally; lobes connected to each other across venter by thickened, protruding crest on anterior margin, more prominent on segment 2; segment 4 with much shorter rounded pair of lateral lobes ( Fig. 6 A–B, D–I). Three pairs of branchiae on segments 2–4, with thick independent filaments progressively tapering to tips, in continuous transverse rows, without medial gap; 8 filaments on segments 2 and 3, 7 on segment 4; filaments progressively longer dorsalwards, and progressively shorter from one segment to another, more marked from segments 3 to 4 ( Fig. 6 A, C, G, J). Entire anterior ventral surface glandular and corrugated until segment 14, more conspicuous until segment 11 ( Fig. 6 A–B, D–I), then continuing as mid-ventral stripe, with distinctly narrow and proportionally elongate mid-ventral rectangles. Notopodia extending until segment 23 on left side of body, 25 on right side; bilobed notopodia, with globular bases and lobes of equal size, progressively longer posteriorwards, first pair slightly shorter than following pairs, notopodia of segments 3–7 placed progressively more laterally, then longitudinally aligned ( Fig. 6 A–J). Winged notochaetae in both rows, wings broader on one margin, twisted, those from anterior row 1/3–1/2 as long as those from posterior row, chaetae of posterior row with wings on distal third only ( Fig. 7 B–D). Neuropodia as fleshy ridges raised from body wall; at least until segment 16, neuropodia bordered by dark pigmentation, becoming paler posteriorly ( Figs 6 A–B, D–I; 7A). Uncini in single, straight rows; uncini with dorsal button at anterior third of base, conspicuous, short prow, curved base and crest with 3 rows of secondary teeth ( Fig. 7 E–I). Nephridial papillae not visible. Pygidium unknown.

Remarks. Of the currently accepted species of Euthelepus , only the type species, E. setubalensis McIntosh, 1885 , E. marchinbar Hutchings, 1997a , and E. kritzleri Londoño-Mesa, 2009 have winged notochaetae in both rows throughout, not presenting serrated chaetae in any region of the body. Of these, only E. marchinbar Hutchings, 1997a is known from Australian waters. Euthelepus setubalensis differs from E. aserrula n. sp. as the former has poorly developed lobes on segments 2–4 and branchiae with single filament on either side of pairs ( Hutchings & Glasby 1986b).

Euthelepus marchinbar described from Northern Australia also has shorter lobes on anterior segments, notopodia extending for 34 segments, until segment 36, and neuropodia beginning from segment 4 ( Hutchings 1997a), while the holotype of E. aserrula n. sp. has notopodia extending until segment 23 on left side of the body, and 25 on the right side, and neuropodia beginning from segment 5, as occurs in all other species of the genus.

Euthelepus kritzleri has lobes of anterior segments with a different morphology from those of E. aserrula n. sp., thicker, not flaring ( Londoño-Mesa 2009). In addition, E. kritzleri has at least 36 pairs of notopodia, extending until the end of the incomplete holotype, and ~15 branchial filaments on segment 2, while in E. aserrula n. sp. there are 8 filaments on segment 2.

Etymology. The specific name “ aserrula ” is Latin and refers to the lack of serrated chaetae.

Habitat. Collected from dead coral substrate from back reef, protected from SE trades in depth of 3– 15 m.

Type locality. Martin Reef, 14°45'22"S, 145°21'46"E, Lizard Island, Great Barrier Reef, Queensland, Australia.

Distribution. Known only from the Lizard Island region.

Figures

FIGURE 6. Euthelepus aserrula n. sp., holotype AM W. 47509. A – B. Entire incomplete worm, left and right lateral views, respectively; C – G. Anterior end, dorsal, three right ventro-lateral views, progressively more lateral, and left lateral views, respectively; H – J. Close ups of anterior end, progressively closer right ventro-lateral and dorsal views. Abbreviations: numbers refer to segments, ll = lower lip, P = prostomium, ul = upper lip. Scale bars: A – D = 0.5 mm, E – G = 0.3 mm, H, J = 0.2 mm, I = 0.15 mm.

FIGURE 7. Euthelepus aserrula n. sp., holotype AM W. 47509. A. Posterior end, right lateral view; B. Notochaetae, segment 5; C – D. Notochaetae, segment 17 under progressively higher magnifications; E – I. Uncini, segments 6, 17 and 30, the latter two under lower and higher magnifications. Scale bars: A = 300 Μm, B – C = 80 Μm, D = 50 Μm, E, G – H = 10 Μm, F, I = 5 Μm.